Solar cells can convert light energy into electrical energy. Solar cells work via photovoltaic effects of the semiconductor materials. Solar cells can be silicon solar cells, gallium arsenide solar cells, or organic thin film solar cells. Among the solar cells, silicon solar cells are most widely fabricated because of their excellent efficiency in energy conversion and low production cost.
A silicon solar cell generally includes a back electrode, a silicon substrate, a doped silicon layer and an upper electrode disposed in that sequence. The doped silicon layer is used as a photovoltaic conversion material, and has a smooth surface for extracting sunlight. The silicon substrate and the doped silicon layer can form a number of P-N junctions, the P-N junctions can produce a number of electron-hole pairs under excitation of the sunlight. However, the area of the smooth surface for extracting sunlight is small, thus an extraction light surface of the solar cell has a small area. Furthermore, when the sunlight irradiates the smooth surface, a part of the sunlight is absorbed by the doped silicon layer, and the other part of the sunlight reflected back by the smooth surface cannot be reused. Therefore, the utilization efficiency of the solar cell is relatively low.
What is needed, therefore, is to provide a method for making a solar cell, and the solar cell with a relatively large extraction light surface.